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CHM020 - Analytical Methods for Biology > Gas Chromatography > Flashcards

Gas Chromatography Flashcards

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1
Q
  • technique used in analytical chemistry for separating and analyzing compounds in complex mixtures
  • relies on the principle of differential partitioning of sample components between stationary phase and mobile phase
  • high sensitivity, selectivity, and efficiency make it an indispensable tool for qualitative and quantitative analysis of organic compounds
A

Gas chromatography (GC)

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2
Q

principle of gas chromatography

A

partitioning equilibrium and interaction between phases

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3
Q
  • inert gas, typically helium or nitrogen, that ocntinuously flows through the system
  • acts like a moving platform, carrying the vaporized sample components through the column
A

mobile phase (carrier gas)

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4
Q

typically, what is the mobile phase (carrier gas)

A

helium or nitrogen

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5
Q
  • thin layer of high-boiling liquid film coating the inner walls of a long, narrow column
  • interacts with the sample components as they travel through the column
A

stationary phase

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6
Q

Two phases of the gas chromatography

A
  1. stationary phase
  2. mobile phase
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7
Q

what happens to the sample in gas chromatography

A
  • vaporized and
  • caried through a colum
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8
Q

strength of the interaction between sample and stationary phase is described by a value called the __ __

A

distribution constant (Kc)

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9
Q

compounds with stronger interactions with stationary phase take __ to elute from the column

A

longer

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10
Q

equilibrium between the concentrations of a compound in stationary phase and the mobile pase

A
  • distribution constant or
  • partition coefficient (Kc)
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11
Q

determines the movement of compounds through the column and thus enables the chromatographic separation

A

equilibrium constant

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12
Q

remove (an adsorbed substance) by washing with a solvent, especially in chromatography

A

elute

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13
Q

where is the stationary phase typically coated on

A

inner walls of column

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14
Q

the stationary phase is typically composed of materials like.. ?

A

silicon grease or wax

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15
Q

what affects separation efficiency by mobile phase

A

flow rate

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16
Q

Components of the Gas Chromatography

A
  1. stationary phase
  2. mobile phase
  3. injector
  4. detector
  5. data system
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17
Q
  • where the sample is introduced into the system
  • vaporizes the sample and injects it into the column
A

injector

18
Q
  • located at the end of the column, it detects separated sample components
  • monitors the eluent leaving the column and provides a signal that correspons to the concentration of the sample components
A

detector

19
Q

collects and analyzes detector output, providing information about sample components’ identities and concentrations

A

data system

20
Q

in gas solid chromatography, the column consists of what?

A
  • hollow tube
  • packed with stationary phase
21
Q

in gas-liquid chromatography, the column is what?

A

coated with thin layer of stationary phase

22
Q

Two types of columns

A
  1. packed columns
  2. capillary columns
23
Q
  • filled with a solid support material, providing a large surface area for interactionb etween the sample components and the stationary phase
  • suitable for separating less volatile compounds
A

packed columns

24
Q
  • have thin, coated layer on the inner walls, providing high separation efficiency and resolving power
  • ideal for separating volatile compounds
A

capillary columns

25
Q

transports the sample through the chromatographic system

A

carrier gas

26
Q

carrier gas must be __, meaning they do not react with the sample or stationary phase, to ensure accurate analysis

A

inert

27
Q

Types of inert gases

A
  1. helium
  2. hydrogen
  3. nitrogen
28
Q
  • most commonly used carrier gas due to its inertness, consistent flow rate, and broad applicability
  • suitable for a wide range of analytical applications and compatible with various detectors
A

helium

29
Q
  • provides higher efficiency and faster analysis compared to helium due to its lower viscosity
  • offers imporved separation of closely eluting compounds
  • however, it is flammable and requires extra safety precautions
A

hydrogen

30
Q
  • inexpensive and readily available carrier gas option
  • less efficient than helium and hydrogen but suitable for routine analyses
  • often used when high-purity heloum or hydrogen is not available or cost is a concern
A

nitrogen

31
Q

Techniques for injecting samples

A
  1. split injection
  2. splitless injection
  3. on-column injection
32
Q
  • divides the smaple into two portions: one directed into the column for analysis and the other vented out
  • suitable for samples with a wide range of concentrations, preventing detector saturation
  • enhances sensitivity for trace-level analytes
A

split injection

33
Q
  • introduces the entire sample into the column without splitting initially
  • ideal for trace-level analysis by maximizing sample concentraton on the column
  • ensures higher sensitivity but requires careful optimization to prevent detector overload
A

splitless injection

34
Q
  • directly introduces the sample onto the head of the chromatographic column
  • suitable for thermally labile compoupnds or sample with a limited volume
  • minimizes sample degradation and provide sharp peak shapes
A

on-column injection

35
Q
  • captures and processes chromatographic data, facilitating data analysis and interpretation
  • converts detector signals into digital information and generates chromatograms, visual representations of analyte peaks
A

recorder or data system

36
Q

Procedure of Gas Chromatography

A
  1. sample injection and vaporization
  2. separation in the column (retention time and peak analysis)
  3. detection and recording of results (interpretation of chromatograms )
37
Q

where is the sample injected into

A

injection port

38
Q

time taken for a compounds to travel from injection to detection

A

retention time

39
Q

identify and quantify sample components based on their retention times and peak areas

A

peak analysis

40
Q

provides insights into sample composition, purity, and concentration

A

interpretation of chromatograms

41
Q

application of Gas chromatography sample

A

metabolomic profiling of human spermatozoa

CHM020 - Analytical Methods for Biology (22 decks)

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